Warning:
Be smart, get a small fan and zip tie it to the heatsink. These cards run hot.
It's fine if you do that, but otherwise may overheat. Overheat issues are a user problem, not a design problem. These cards are designed for servers with great airflow. A directly attached fan provides this.
Drivers:
Can be ran on windows 10, you need to find the qlogic drivers for server 2012 if you are having issues with shutdown/restart. Otherwise the HP drivers work fine for me.
Linux has no issue with drivers. Just set the MTU (Linux INCLUDES VyOS)
FreeNAS 11.2 + has no issue with drivers. All I did was set the MTU (Freenas being on top of FreeBSD means that PFsense is likely to have no issues as well)
SFP+ Module support:
I can only speak for cisco modules but they worked fine. I had a SFP+ DAC and LC Tranceiver (10GBe) from cisco, they all worked fine.
In my experience SFP+ cards seem to have no issues with SFP+ modules, it's the switches you've got to watch out for. They can have compatiability issues.